Mobile gas detecting unit with distance traveled marking means



1, 1967 c. A. HEATH ETAL 3,333,458

MOBILE GAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANS FiledDec. 12, 1963 8 Sheets-Sheet 1 ATTORNEYS 1, 1967 c. A. HEATH ETAL3,333,458

MOBILE vGAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANS FiledDec. 12, 1963 8 Sheets-Sheet 2 mPows/ v /22 0/00/26? 0 @FWMCE 2 //.5cvczfs vars Blow/E2 894/ Q Qfi' L. 500M 2.50am 72/ W vn ME 54 g; U ca/meazowm A 5mm BOOM 5PAAI' 6A6 INVENTORS CHARLES A. HEATH JOHN F. HOLLANDATTORNEYS Aug. 1, 1967 C. A. HEATH ETAL MOBILE GAS DETECTING UNIT WITHDISTANCE TRAVELBD MARKING MEANS Filed Dec. 12, 1965 8 Sheets-Sheet 5INVENTORS CHARLES A. HEATH JOHN F. HOLLAND ATTQRNEXS Aug. 96 c. A. HEATHETAL 3 MOBILE GAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANSFiled Dec. 12, 1963 8 Sheets-Sheet 4 o Q v Q 'I'IIIJ'II INVENTORSCHARLES A. HEATH JOHN F. HOLLAND Aug. 1. 1967 C. A. HEATH ETAL MOBILEGAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANS Filf l Dec. 12.1963 8 Sheets-Sheet '5 CHARLES A. HEATH JOHN F. HOLLAND ATT EYS.

Aug. 1, 1967 c. A. HEATH ETAL 3,

MOBILE GAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANS Filed Dec12, less 8 Sheets-Sheet 6 INVENTORS CHARLES A. HEATH JOHN F. HOLLAND A TTORNEY 1, 1967 c. A. HEATH ETAL 3,333,458

MOBILE GAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANS I F l dDec. 12, 1963 s Sheets-Sheet 7 GEM-"470? Yul 79 vA/emc V f I W U VAR/AC75 m Ill lll'lll: l2?

' ://6 C iazowfie I17 98 2000 n Y W 3 W W W M /o E. 800M M2 447 /27 1/ WM8 2000a /22 4 2 27 i T g, I /22 fl/ I491 200011 /ZZ 246 I /0 w. /47!- IL c. 500M J 1 [/27 yaw E/28% 2000.0. {22 /24c /49c ,0 tenor:

1 me I lSZc K Mac INVENTORS CHARLES A. HEATH JOHN F. HOLLAND ATTORNEYSg- 1, 9 (LA. HEATH ETAL 3,333,458

MOBILE GAS DETECTING UNIT WITH DISTANCE TRAVELED MARKING MEANS FiledDec. 12, 1965 8 SheetsSheet 8 I as iNVENTORS CHARLES A. HEATH JOHN F.HOLLAND E .15 ll,

AT TORNEYVS United States Patent 3,333,458 MOBILE GAS DETECTING UNITWITH DISTANCE TRAVELED MARKING MEANS Charles A. Heath, Richmond, andJohn F. Holland, De-

troit, Mich, assignors to Heath Survey Consultants, Inc., WellesleyHills, Mass., a corporation of Massachusetts Filed Dec. 12, 1963, Ser.No. 330,060 2 Claims. (Cl. 73--23) This invention relates toimprovements in mobile gas detecting apparatuses, and more particularlyto a mobile gas detecting unit incorporating a novel and improvedrecording chart marking system for establishing a predetermined distancetraveled reference scale on the chart paper'of a recorder to provide ameans to mark gas leak locations accurately relative to land marks alongthe selected survey route.

The prior art mobile gas detecting units which automatically detect andrecord concentrations of gases or gas in the atmosphere, such as fuelgases, along a preselected route are not capable of providing a graphicrecord which indicates any scale on the recorder chart so that anaccurate and exact leakage chart can be made. When using such prior artdetecting units, without any marking to indicate a reference scale onthe recorder chart paper of the distance traveled, the mobile units musttravel at a constant speed and this is difficult to maintain. Such aconstant speed is required in order to permit interpretation of thedistance traveled from the prior art type charts. Fluctuations in thespeed of the mobile unit employed in said prior art units provide errorsbecause there are no markings on the recorder chart to indicate wherethe vehicle may have changed its speed. Accordingly, it is the primaryobject of the present inventi-on to provide a novel and improved mobilegas detecting apparatus which incorporates a predetermined distancetraveled marking system, for establishing a reference scale on therecorder chart paper, to compensate for any changes in the speed of thevehicle carrying the apparatus.

It is another object of the present invention to provide a novel andimproved mobile gas detecting apparatus which includes a system foraccurately marking gas leak locations relative to the landmarks along apreselected survey route, whereby an exact distance traveled referencescale can be made at any travel point on a recorder chart paper,regardless of the travel speed of the vehicle carrying the unit.

It is still another object of the present invention to provide a noveland improved mobile gas detecting unit which includes a simple andcompact distance traveled marking means which is efiicient and accuratein operation, and which provides a reference scale on the gas detectingunit recorder chart paper, whereby a gas leak may be accurately locatedrelative to a landmark.

It is a further object of the present invention-to provide a novel andimproved accurate method of detecting and measuring a concentration ofgas .or gases in the atmosphere along a preselected survey route bymeans of a mobile gas detecting apparatus which includes a chartrecorder, and which methodincludes the novel steps of moving therecorder chart paper at a constant speed and automatically marking apredetermined distance tarveled reference scale on the recorder chartpaper for accurately locating gas leaks relative to landmarks.

It is still another object of the present invention to,

provide a novel and improved mobile gas detecting apparatus fordetecting and charting the location of leaks of a preselected gasthrough the surface of the ground comprising a vehicle adapted to moveover the ground along a predetermined survey route; a gas sample pickupapparatus operatively mounted on said vehicle; a suc- 3,333,458 PatentedAug. 1, 1967 tion means for drawing gas samples through said gas pick-upapparatus; analyzing means for measuring the concentration of saidpreselected gas in the gas samples drawn by said suction means;recording means including a chart and a first and a second stylus; saidrecording means being responsive to said analyzing means for recordingthe concentration of said preselected gas on said chart by means of saidfirst stylus; means responsive to the movement of said vehicle foractuating said second stylus for marking a distance traveled referencescale on said chart, whereby a continuous strip chart is produced whichshows detected gas leaks in reference to the distance traveled by thevehicle.

Other objects, features and advantages of this invention will beapparent from the following detailed description, appended claims, andthe accompanying drawings.

In the drawings:

FIG. 1 is a schematic perspective view of a mobile gas detecting unitmade in accordance with the principles of the present invention, andwith parts of the vehicle broken away, and showing the detecting unitmounted in a motor vehicle;

FIG. 2 is a front perspective view of the mobile gas detecting unitillustrated in FIG. 1;

FIG. 3 is a schematic view of a first embodiment of a fifth wheelapparatus for actuating the fifty-foot interval marking means, from theperiphery of one of the wheels of the vehicle of FIG. 1;

FIG. 4 is a fragmentary schematic view, in perspective, of a secondembodiment of a fifth wheel apparatus for actuating the fifty-footinterval marking means, by direct engagement of the fifth wheel with theground over which the mobile gas detector moves;

FIG. 5 is a schematic view of a gas sampling system for use with thepresent invention;

FIG. 6 is a diagrammatic view of a chart recorder employed in thedetecting unit of the present invention;

FIG. 7 is a diagrammatic view of a switchboard for use in the presentinvention;

FIG. 8 is an enlarged fragmentary plan view of the boom structure shownin FIG. 2, taken along the line 8-8 thereof and looking in the directionof the arrows;

FIG, 9 is a fragmentary, elevational sectional view of the structureillustrated in FIG. 8, taken along the line 99 thereof, and looking inthe direction of the arrows;

FIG. 10 is a horizontal sectional view of the structure illustrated inFIG. 9, taken along the line 10-10 thereof, and looking in the directionof the arrows;

FIG. 11 is a fragmentary enlarged view of the gas sampling boomsupporting structure employed in the invention;

FIG. 12. is a fragmentary horizontal view of the structure illustratedin FIG. 11, taken along the line 12--12 thereof, and looking in thedirection of the arrows;

FIG. 13 is a schematic view of an illustrative wiring diagram for thedetecting unit of the present invention;

FIG. 14 is a central elevational view of a primary sampling funnelemployed in the invention; and

FIG. 15 is a top plan view of the structure illustrated in FIG. 14,taken along the line 1515 thereof, and looking in the direction of thearrows.

Referring now to the drawings and in particular to FIGS. 1 and 2, thenumeral 10 generally designates a motor vehicle in which is incorporateda gas detecting unit made in accordance with the principles of thepresent invention. Any suitable motor vehicle may be employed, and afour-wheeled drive vehicle is preferable. The mobile gas detecting unitof the present invention includes a hydraulically operated gas samplepick-up boom structure which is generally indicated by the numeral 11,the gas sample distribution system generally indicated by the numeral 12in FIG. 5, and the gas oxidizer and gas analyzer generally indicated bythe numerals 13 and 14 in FIGS. 1 and 5. The mobile gas detecting unitfurther includes a chart recorder generally indicated by the numeral 15in FIG. 1. The operation of the aforementioned units of the mobile gasdetecting apparatus are described in detail hereinafter.

As shown in FIGS. 1 and 2, the gas sample pick-up boom structure 11includes a sampling funnel 16 which is connected at its upper end to thelower end of a suitable flexible conduit or tube 17 by any suitablemeans, as by the hose clamp 18. The upper end of the flexible conduit 17is connected by means of the hose clamp 20 to the outer end of thetransversely disposed rigid conduit or pipe 19 on the front end of thevehicle 10.

The funnel 16 is supported by a flexible suspension means generallyindicated by the numeral 21 in FIGS. 1, 2, 8, 9 and 10. The suspensionmeans 21 is free to swing in any direction and maintain the bottom ofthe funnel on an even plane for uniform suction of the gas samples fromthe atmosphere. The funnel 16 is thus supported for universaladjustability in case it hits an object as the vehicle 10 moves alongits preselected survey route. As best seen in FIGS. 8, 9 and 10, theflexible suspension means 21 includes the collar 22 which is' mounted onthe outer end of the boom pipe 19 and secured in place by any suitablemeans, as by a lock screw 23. Integrally formed on the lower side of thecollar 22 is a horizontal journal member 24 through which is formed thebore 25 at a position transverse to the longitudinal axis of the boompipe 19. Rotatably mounted in the bore 25 is the transversely disposedshaft 26 which is held against axial movement by any suitable means, asby the cotter keys 27 and washers 28.

As shown in FIG. 8, a hole 29 is formed through the shaft 26 at each endthereof and these holes are disposed parallel to the longitudinal axisof the boom pipe 19. The flexible suspension means 21 further includesthe pair of rods 30 which are provided on the upper ends thereof withthe right angle turned portions 31, as shown in FIGS. 8 and 9. The rodportions 31 are rotatably mounted in the holes 29 and are retained inplace by any suitable means, as by the cotter keys 32. The lower ends ofthe rods 30 are threaded, and threadably mounted thereon are thethreaded connector members 33. Threadably mounted in the lower ends ofthe connector members 33 are a pair of rods 34 which are similar to therods 30 and which have a reverse thread on the upper ends thereofwhereby when the connector members 33 are turned in an appropriatedirection, they will either draw the rods 34 upwardly toward the rods30, or they will separate said rods, as desired. The lower ends of therods 34 are turned outwardly at right angles thereto as indicated by thenumerals 35. The suspension means 21 further includes the horizontallydisposed channel member 36 which is secured to the upper end of thefunnel 19 by any suitable means, as by means of the U-bolt 37 and thelock nuts 38. The right angle rod ends are adapted to be rotatablymounted in the holes 39 which are for-med through the vertical wall ofthe channel 36. The holes 39 are disposed in parallel alignment with theholes 29 in the upper shaft 26. The rod ends 35 are secured in thechannel 36 by means of the cotter keys 40.

As best seen in FIGS. 2 and 12, the boom pipe or conduit 19 isadjustably mounted on the vertical boom carrier plate'41 which isnormally disposed in a horizontal position. Fixedly mounted on the frontside of the plate 41 by any suitable means, as by welding, is a pair 7of U-shaped clamp members 42 which are adapted to slidably receive theinner side of boom pipe 19. A pair of mating U-shaped clamps 43 areadapted to enclose the outer side of the pipe 19 and to be releasablysecured to the clamp members 42 by means of the bolts 44.

The vertical plate 41 is hingedly connected to the 4 bracket arm 46 bymeans of the bolt 45. The bracket arm 46 is fixed to the sleeve 47. Thesleeve 47 is rotatably mounted on the vertical boom supporting post 48so as to permit the plate 41 to be swung on a horizontal plane about thepost 48. As best seen in FIG. 11, the

lower end of the post 48 is fixedly secured to a mounting bracket 49 byany suitable means, as by welding. The mounting bracket 49 is fixedlysecured to the front bumper 50 of the vehicle by any suitable means, asby the rivets 51. The sleeve 47 is held in a vertically adjustedposition on the post 48 by means of the collar member 52 which may besecured in an adjusted position on the post 48 by means of the lockscrew 53.

As shown in FIGS. 1 and 2, the post 48 is further supported by thediagonal brace 54 which is secured to the front bumper 50 by anysuitable means, as by the rivet 55. The upper end of the brace 54 iswelded to the collar 56 which is secured in place on the post 48 bymeans of the lock screw 57. A rearwardly extended diagonal brace 58 hasthe front end thereof fixedly secured to the collar 56 and the rear endthereof welded to the front fender 59 of the vehicle.

As shown in FIGS. 2, 11 and 12, the boom carrier plate 41 is adapted tobe maintained in any desired adjusted pivoted position relative to thepivot bolt 45 by means of the hydraulic cylinder generally indicated bythe numeral 60. The lower end of the hydraulic cylinder 60 is providedwith the attachment bracket 61 for pivotally attaching the cylinder tothe inner end of the plate 41 by any suitable means, as by means of thepivot pin or bolt 62. The hydraulic cylinder 60 is provided with theusual piston 63 and the piston rod 64. The piston rod 64 extendsupwardly from the cylinder and is provided on the upper end thereof withthe yoke member 65. The yoke member 65 is pivotally mounted at the point66 to the bracket 67 carried on the collar 68. The collar 68 isrotatably mounted on the upper end of the post 48 and is retained in anadjusted position on the post against vertical movement by means of theretainer collars 69 and 70 which are secured on the post 48 by means ofthe lock screws 71 and 72, respectively.

The pick-up boom carrier plate 41 is adapted to be normally biasedinwardly, to the position shown in FIGS. 1 and 2, by means of thetension spring 73 which is shown in FIG. 12. One end of the spring 73 isattached to the inner side of the plate 41 by any suitable means, as bymeans of the U-bolt 74. The inner end of the spring 73 is attached tothe front end of the vehicle 10 by any suitable means, as by means ofthe U-bolt 75. It will be seen that if the funnel 16 strikes an object,the plate 41 will be moved clockwise, as viewed in FIG. 12. and it willbe returned to the position shown in FIG. 12 by means of the tensionspring 73 after the funnel 16 has cleared said object.

The hydraulic cylinder 60 may be operated by means of a remote controlfrom the inside of the vehicle 10. As shown in FIG. 13, the hydrauliccylinder 60 may be supplied with hydraulic fluid from a suitablereservoir 76 by means of the pump 77 which is driven by a suitableelectric drive motor 78. The drive motor 78 is powered from a suitableportable source of 110-volt electrical energy, as for example thegenerator 79, which would be located in a suitable position in thevehicle 10. The ground lead of the generator 79 is connected to thepower supply line 80. The other lead of the generator 79 is connected bythe lead wire 82, master switch 83, and a suitable variable resistor 84,to the other power supply line 85.

The power supply lines 80 and are connected to the motor 78 by means ofthe lead wires '86, '87 and 88 and the switch 89. The pump 77 would drawhydraulic fluid from the reservoir 76 by means of the conduit 90 anddeliver it to the pressure fluid conduit 91 which is connected to thefour-way flow control valve 92. The

fluid would be exhausted from the valve 92 by means of the exhaustconduit 93 which is connected to the reservoir 76. The four-way valve 92may be disposed in the vehicle at any desired position for remotelycontrolling the operation of the cylinder 60, to raise or lower the boom19 as desired. The valve 92 controls the feeding and ex hausting of thehydraulic fluid to the desired end of the cylinder 60 through theconduits 94 and 95. The pick-up boom pipe 19 may be made to any desiredlength. In some models it has been found that a boom pipe 19 of aboutsix feet in length is desirable so that it may extend about five feetoutwardly from the side of the vehicle 10. The hydraulic pump 77 may bedisposed in any suitable position in the vehicle 10, as'for example, itmay be disposed on the front end of the vehicle, as shown in FIG. 2.

As shown in FIG. 2, the outer end of a second flexible conduit or tube99 is connected to the inner end of the boom pipe 19 by means of thehose. clamp 100. The flexible conduit 99 is connected at the other endthereof to the inlet valve 101 of the gas sampling system shown in FIG.5. The valve 101 is a three-way flow control valve which is preferablymounted on the front of the vehicle 10, in front of the radiator.However, it should be understood that the valve 101 may be mounted inany suitable position on the vehicle 10. The gas sampling system inletvalve 101 is provided with the three large inlet tubes 102, 103 and 104,and the outlet tube 105. As best seen in FIG. 5, the inner end of theflexible conduit 99 is connected to the inlet tube 102 by means of thehose clamp 106.

It will be understood that the aforedescribed'gas sample pick-up boom isillustrative of the type boom which may be connected to each one of thethree inlets 102, 103

and 104 on the valve 101. FIGS. 1 and 2 show such a pick-up boom mountedon the right side of the vehicle and a similar boom wouldbe mounted onthe left side of the vehicle and on the center of the vehicle.-

The valve inlets 102, 103 and 104 are provided with suitable gate valvesgenerally indicated by the numerals 107, 108 and 109. It will beunderstood that any suitable type of valve may be employed to carry outthe function of said gate valves, and that they may be manually orautomatically operated so that any desired inlet may be selectivelyoperated. As shown in FIG. 5, one end of a flexible conduit 110 isconnected by means of the hose clamp 111 to the discharge end of thevalve outlet tube 105. The other end of the conduit 110 is connected bymeans of the hose clamp 112 to the inlet 113 of the suction blower 114.The suction blower 114 may be of any suitable type and is adapted todraw a gas sample through a primary sampling system comprising thefunnel 16, the conduit 17, the boom pipe 19, the conduit 99, the inletvalve 101, and the connecting conduit 110. The suction blower 114 may betermed the primary sampling pump and it exhausts to the atmosphere onlythrough the outlet 123.

As shown in FIGS. 7 and 13, the blower 114 may be controlled by a switch115 mounted on a control panel 116. The lead wire 117 connects one sideof the blower 114 to the power line 80. The other side of the blowermotor is electrically connected to the power line 85 by means of thelead wires 96, 98 and 120, the fuse 119; switch 115, and the variableresistor 121. The numeral 122 indicates signal lights throughout thevarious parts of the circuit of FIG. 13.

The primary sampling pump 114 is preferably a universal variable speedtype motor and its speed may be varied by the series connected voltageregulator 121 for varying the rate of flow of the primary gas samplethrough the primary sampling system, as more fully explainedhereinafter. A suitable pump 114 is a conventional vacuum sweeper blowerhaving a capacity of from 3000 to 6000 cubic feet per minute.

As shown in FIGS. 1 and 2, the secondary sampling system includes .areduced diameter flexible hose or tube 133 disposed inside of the boompipe 19 and the flexible tubes 17 and 99, The outer end of the flexiblehose 133 is connected to an intake nozzle which is disposed in thethroat of the funnel 16. As shown in FIG. 5, the reduced diameter hose133 extends into the flow control valve inlet 102, and it extends outthrough the side of the inlet 102 and is connected to the conventionalfilter 126. The hose 133 emerges from the flow control valve inlet tube102 on the outer side of the gate valve 107. The filter 126 is connectedby means of the conduit to the electrically operated solenoid valve 128which is in turn connected by means of the flexible conduits 136, 137,138 and 130, to the inlet 131 of the secondary sampling suction pump132. The pump 132 is a constant speed pump of any suitable type, as forexample, it may be a carbon vane or diaphragm type, sealed pump. Asuitable piston pump is one sold by Bell and Gossett Company of MortonGrove, 111., Model SYC-LV.

As shown in FIG. 5, the flow control valve inlet 103 is provided with aninternally mounted reduced diameter sampling hose 139 which is similarin structure and function to the sampling hose 133. The sampling hose139 emerges from the inlet 103 and is connected to the conventionalfilter 126a. The filter 126a is connected to the secondary pump inlet131 by means of the conduits 140, 141, 138 and 130, and the electricalsolenoid operated valve 12812. The flow control valve inlet tube 104 isprovided with a similar reduced diameter sampling tube 142 which isconnected to the filter 1261). The filter 12Gb is connected by means ofthe flexible tube 143 to the electric solenoid valve 12817. The solenoidvalve 1281) is connected by means of the flexible conduits 1'37, 138 and130 to the inlet 131 of the secondary suction pump 132.

The secondary sampling system of FIG. 5 is adapted to be connected to aremote gas sample pick-up or probe for checking off-street areas. Thenumeral 144 indicates a flexible gas sample hose which may be connectedat one end thereof to a remote probe and at the other end thereof to theconventional filter 1260. The filter 1260 is connected to the secondarysuction pump 132 by means of the conduits 145, 146, 138, 130 and theelectric solenoid valve 1280. The remote probe would be constructed inthe same manner as probe 16 and would be connected to pick-up primaryand secondary samples.

As shown in FIG. 13,. the solenoid valves 128 through 1280 are eachconnected to the power lines '80 and 98 by the lead wires 147 through1470, the lead wires 148 through 148e, the switches 149 through 1490,and the fuses 124 through 124c. The last mentioned circuits may each beprovided with an indicator light 122.

As shown in FIGS. 7 and 13, the secondary pump 132 would be connected tothe power lines 80 and 98 by means of the lead wires 150 and 151, fuse125. switches 152 through 1520, and lead wires 127 through 1270. It willbe seen that the secondary pump 132 is connected in parallel with thesample line solenoids 128 through 128C and it operates only when any oneof these solenoids are open, because the switches 149 are interconnectedwith the switches 152. The control switch 89 for the right boom may alsobe located on the control board 116. Switches 89a and 89b for the leftand center booms which would be connected to valve inlets 103 and 104,if used, may also be mounted on the control board 116.

As shown in FIG. 5, the secondary sampling pump 132 delivers a gassample to the oxidizer 13 by means of the outlet 153 and the conduits154 and 155. The conduit 154' is connected to the atmosphere by means ofthe conduit 156.

The oxidizer or furnace 13 is adapted to burn off the heavyhydro-carbons of exhaust gases which may be in the gas samples drawnthrough the secondary sampling system, and it may be of any suitabletype. The oxidizer 13 burns oif objectionable gases at a temperaturelower than the burning temperature of the selected gas, as methane, soas to. allow the selected gas to pass through the oxidizer to the gasanalyzer 1 4.

The oxidizer 13 is schematically illustrated and comprises an insulatedcontainer "158 in which is mounted the U-shaped metal tube 159 which ismade from Inconel (a trademark) metal or any other suitable metal. Oneend of the metal tube 159 is connected to the non-conductive inlet tube155 and the other end thereof is connected to the analyzernon-conductive inlet tube 161 Both ends of 159 are electricallyinsulated from the tubes 155 and 160. The metal tube 159 has a highresistance characteristic and is used as a heating element. The metaltube 159 is connected to a source of electrical power by means of thetransformer 162 and the lead wires 163 and 164. The transformer 16 2 isconnected to the power lines and by means of the variable resistor 165and the switch 166 and lead wires 157 and 161, and fuse 129. Thetemperature in the oxidizer 13 is controlled by the variable resistor165 which may be controlled from the control board 116. The diameter andlength of the tube 159 is calibrated so that a low voltage-high amperagecurrent applied across the inlet and outlet of the tube will providetemperature ranges adequate for burning olf the objectionable gases. Theresistor 165 regulates the primary side of the transformer 162 to obtainthe low voltage amperage current. The temperature inside of the oxidizer13 can be checked by any suitable means, as for example, by thethermocouple 167 as shown in FIG. 5. The thermocouple 167 is operativelyconnected to the meter 218 to provide for accurate regulation of thetemperature of the oxidizer. The meter 218 is calibrated to read thethermocouple output directly in temperature.

As shown in FIG. 5, the numeral 168 indicates a cylinder of span gascomprising methane mixed with air for supplying the same to the oxidizer13 for calibrating the analyzer 14. The cylinder 168 is connected to theoxidizer 13 by means of a control valve 169, the conduit 170, theelectrically operated solenoid valve 171, the conduit 172, hand valve173 and conduits 174 and 155. The solenoid valve 171 would be connectedto the power lines 89 and 85, as shown in FIG. 13, by means of the leadwires 175 and 176 and the control switch 1'77.

The gas analyzer 14 may be any suitable high sensitivity methanedetector capable of detecting methane in the range of about one partmethane in a million parts of the gas sample. Preferably, the gasanalyzer should be a flame-ionization analyzer. A suitableflame-ionization analyzer is one made by the Davis Emergency EquipmentCompany, Newark, N.J., Model No. 11-6505.

As shown in FIG. 5, the numeral 178 indicates a hydrogen supply cylinderwhich is adapted to feed hydrogen through the conduit 179 to theanalyzer 14 as fuel for the flame-ionization cells. The output voltagefrom the analyzer 14 is transmitted by means of the lead wires 180 and181 into the recorder 15. The recorder 15 may be of any suitable type,which is equipped with an extra stylus as 192, for use in connectionwith the fifty-foot recording device, as more fully explainedhereinafter. The input signalfrom the gas analyzer is conducted to thestylus 182 which operates in the usual manner to draw an ink strip 183on the moving chart paper 1 84 of the recorder 15. As shown in FIG. 6,the variations in the path traced by the stylus 182 which extend to theleft on the chart paper, indicate the concentration of the methane gasor other gas being detected. The marks which are made toward the rightside of the paper indicate a reference mark, as for example, a buildingor a given street number along the survey route. The chart paper 184-may be calibrated so that the full width of the paper would indicate acertain concentration of methane in the sample. As, for example, onehundred parts per million parts of sample could be equivalent to a fullsweep of the stylus 182 across the entire width of the chart paper. Themark 185 could be selectively made by means of a foot pedal 186 whichwould beconnected to a suitable source of 6 power to insert a reverse ornegative signal through the lead lines 187 and 188 into the recordercircuit of the stylus 182. The stylus 182 maintains a straight lineuntil methane is detected and then it moves sidewardly in proportion tothe concentration of methane in the sample.

The recorder 15 is provided with the usual controls and moves the paper184 at a constant speed. Thenumeral 189 indicates the on-off switch. Thenumeral l9il'indicates the input selector switch. This provides thenecessary input connections to obtain a 10 millivolt range on therecorder span. The numeral 191 indicates a control means for controllingthe zero setting of the operating stylus 1 82.

As shown in FIG. 6, the numeral 192 indicates a second stylus which isadapted to make a mark on the chart paper '18 1- for a predeterminedunit of travel, as every fifty foot travel of the vehicle 10. The stylus192 makes a mark as 193 when it is energized sidewardly by theelectrical solenoid generally indicated by the numeral 194. The solenoid19 4 would be energized by an impulse signal sent to it through the leadwires 195 and 196 from the travel impulse generator generally indicatedby the numeral 197 in FIG. 3.

In FIG. 3 the numeral 198 indicates one of the drive wheels of thevehicle 19. A take-off wheel 200 is adapted to engage the periphery ofthe drive wheel 198 and be driven thereby. The take-off wheel 260 isrotatably mounted on a suitable shaft 201 which is supported by the arms202 and 293 from the vehicle frame 294. The circumference of thetake-off wheel 200 is such that when used in conjunction with the gearreducer 206, the angular output of the gear reducer will have onerotation for each linear foot traversed by the vehicle '14 It does notmake any difference what the circumference of the vehicle wheel 198comprises. A flexible drive shaft 295 is connected to one end of thetake-off wheel shaft 201 by any suitable means, and the other end of theflexible shaft 295 is connected to the input shaft of a suitable gearreducer generally indicated by the numeral 206. A second flexible shaft297 is connected at one end thereof to the output shaft of the gearreducer 2% and at the other end thereof to the input shaft 208 of theimpulse generator 197. The input shaft 298 is connected to a drive shaft209 which is journalled in the supports 211] and 211. The shaft 299 isconnected to a worm gear 212 which is meshably engaged with a pinion213. The pinion 213 is provided with a switch operating arm 214 foroperating the micro-switch 215 upon one complete turn of the pinion 213.The microswitch 215 controls the flow of direct current electrical powerfrom a suitable source through the lead wires 195 and 196 to thedistance marking stylus 192 (FIG. 6). The sPoIIgce of DC power isindicated by the numeral 216 in The gear reduction ratio of the gearreduction unit 206 and the size of the circumference of wheel 2% areselected to provide a proper calibration for the impulse generatorwhereby the input to worm 212 makes one complete revolution for each onefoot travel of the vehicle 10. Therefore, fifty turns of the worm 212will rotate the pinion 213 one complete revolution to actuate themicroswitch 215 once for every fifty foot travel of the vehicle. Thestylus 192 makes a vertical line, as shown in FIG. 6, until it is givenan impulse from the generator 197 whereby it makes the horizontal mark193 to indicate fifty feet of vehicle travel. As the vehicle goes fasterthe fifty foot marks 193 will be closer together on the chart paper 184.The chart paper 184 is run at a constant speed and this speed can be anyvalue just as long as it is consistent.

'FIG. 4 indicates a modified take-off wheel construction in which thetake-off wheel 260a is adapted to engage the ground 217 over which thevehicle is traveling. The takeolf wheel 29011 is connected to thevehicle frame 204 by means of a pair of support arms 203a and the hingepin 230. The wheel 200a drives the flexible cable 205a for generating animpulse current in the same manner as de- 9 scribed for the embodimentof FIG. 3. The wheels 200 and 200a may be raised and lowered intooperative position by any suitable means, as by the hydraulic motor 231,shown in FIG. 4.

FIGS. 14 and illustrate a preferred sampling funnel which shows thesecondary sampling pick-up nozzle 123 located at the throat of thefunnel 16. As shown in FIG. 14, the funnel 16 comprises the cylindricalintake portion 219 which is approximately ten inches in diameter and 2%high. Integrally connected to the upper end of the portion 219 is theupwardly converging throat portion 220. Fixedly connected to the upperend of the throat portion 220 is the connector pipe 221 to which isconnected the flexible tube 17.

The nozzle 134 is preferably made from /2" brass pipe and is enclosed atthe lower end thereof with a threadably mounted screw 222. As shown inFIG. 14, the lower end of the nozzle extends partially into the funnelthroat portion 220 and the nozzle portion in the throat 220 is providedwith a plurality of A3 diameter holes 223 which are formed through theside walls of the nozzle 134. A crossbar 224 is fixedly mounted in theconnector pipe 221 and is provided with a threaded hole 225 in which isthreadably mounted the upper threaded end of the noZZle 134.

The nozzle is adjustably secured in place in the member 224 by means ofthe tubular connector members 226 and 227 which are formed as threadedsleeves and welded to the upper and lower sides of the cross member 224.A lock nut 228 fixedly secures the nozzle 134 in an adjusted position.The upper end 229 of the nozzle 134 is provided with a plurality ofserrations -for gripping the secondary suction hose 133.

It will be understood that the flame-ionization detecting instrument 14is sensitive to all hydrocarbons. It is a carbon atom counter. Bycontrolling the temperature of the oxidizer 13 to the point where onlymethane gas can pass through the flame ionization unit 14, this unitbecomes selective to methane. By lowering the temperature of theoxidizer 13, it is possible to allow propane or butane gas to passthrough and be detected on the flame-ionization unit 14.- This functionis not possible with an infra-red type detector where selectivity andsensitivity to any predetermined gas must be built into the instrument.Major changes are necessary in order to convert the sensitivity of aninfra-red detector to another gas than that for which it was designed.It is thus seen that the combination of the oxidizer 13 and theflame-ionization unit 14 provides a detecting unit which is flexible andcan be quickly changed to any sensitivity desired to detect a pluralityof gases.

It will further be seen that the secondary sample pump 132 exhausts tothe atmosphere and it is used only to transfer the gas sample from thenozzles 134 in the funnels 16 to a point near the oxidizer 13 as rapidlyas possible. The minimum delay in transferring the gas sample throughthe secondary sampling system to the oxidizer promotes more accurateplotting of gas leaks. The percentage of error is reduced in proportionto the increase in speed and response of the entire detecting system.

The actual gas sample which is analyzed by the analyzer 14 is taken atthe junction of the conduits 154 and 155 where the secondary pump 132exhausts to the atmosphere. The analyzer sample is pulled through theionization cell of the flame-ionization instrument by a third built-inpump and, therefore, the sample is below atmospheric pressure as itpasses through the analyzer 14. The span gas from the cylinder 168 isalso introduced to the conduit 155 against only atmospheric pressure andit is pulled through the analyzer 14 by the suction pump which is anintegral part of the aforementioned flame-ionization unit. The secondarypump 132 does not operate during the span cycle or calibration period.The secondary sampling pump 132 runs only when one or more of thesampling line solenoid valves128 through 1280 are open and operating.

It will be understood that the holes 223 formed in the secondary nozzle134 are made to a size to allow adequate passage of the gas samplewithout restriction into the secondary line 133. The holes are madesmall enough, however, to prevent entry of dirt particles which mighttend to clog the secondary lines. The intake nozzle 134 is exposed toweather conditions and moisture and, accordingly, it must be constructedfrom a material which will resist corrosion and rust. Stainless steel isdesirable, but brass will serve the purpose.

It is necessary to maintain a correct differential in vacuum between theprimary sampling system and a secondary sampling system, and this is oneof the reasons for using a universal type constant speed motor in thesecondary pump 32 and the variable speed motor in the primary blower114. Varying the speed of the blower 114 changes the rate of flow in theprimary sampling line, however, this result could be achieved with aflow control valve in the suction line between the suction blower 114and the three-way sample distribution valve 101.

The primary sampling system functions to develop a negative pressure inthe funnel 16 and the immediate area between the lower opening of thefunnel and the surface that is being sampled for leakage. This negativepressure would be in relation to normal atmospheric pressure at anygiven period and it is necessary for the purpose of bringing the sampleinto contact with the secondary pickup nozzle 134 at the throat of thefunnel 16. Correct adjustment of the primary air fiow can compensate forchanges in barometric pressure, which afiects the venting of gas leakagefrom the soil, and within reason, can counter the effects of surfacedrafts and winds which tend to deflect the venting gas as it leaves thesoil. If the suction blower 114 is operated at too low a speed, thedesired affect is not accomplished. If the speed of the blower 114 istoo high, the sample can be drawn past the secondary pick-up nozzle 134too rapidly to permit optimum transfer of the sample to the secondarypick-up line 133. This action would result in part due to the increasedspeed of the primary sample past the secondary pick-up and also to thecounter action of the increased vacuum of the primary sample in relationto that of the secondary vacuum pump 132, which is constant.

In practice, the location of the secondary pick-up nozzle 134 in thefunnel 16 and the correct operating speeds or voltage regulator settingfor adjusting the speed of the primary blower 114 for various conditionsare established by testing each of the sampling systems. The operatingstandards or settings are recorded and can be used by the operator asthe various winds or barometric changes are encountered. The standardsare determined by disposing the detecting unit over known gas leaks andadjusting the differential between the primary and secondary gassampling systems until a maximum reading is made on the recorder. Thiscalibration operation for setting the operating standards can be carriedout under various wind and barometric pressure conditions and the propersettings recorded for future use.

The sampling system of the present invention provides flexibility inadjusting to changing weather conditions and increased sensitivity byreducing the dilution of the sample during transfer from the point ofentry into the secondary sampling system and the point of detection inthe gas analyzer 14. There is less dilution in the small diameterconduit 133 where the sample travels as an elongated slug, with only thesmall area at the front and rear of the slug exposed to the air thatwould tend to dilute it. In the large diameter conduit 17, a muchgreater area of the sample is exposed to dilution in proportion to theamount of the sample being conducted. This is a critical point in thedetermination of the efficiency of a sampling technique.

Two factors are involved in a sampling technique. First, the amount ofgas concentration in a sample that reaches the gas analyzer is indicatedby the reading on the meter or the deflection of the stylus 182 on thechart paper 184. If the sample is diluted enroute from the point ofpick-up to the instrument 14, the accuracy of the process is adverselyaffected. The other factor is the amount or volume of actual sample thatis available as the sampling funnel 16 passes over a leak. If the leakis small and not spreading over a wide area as it passes through thesoil from the source on the gas main, very little sample would beavailable during the time the intake funnel 16 passes over the leak. Inthis case, any dilution within the sampling system would tend to limitthe ability of the mobile unit to detect small leaks. This point must beconsidered when the sampling boom does not pass directly over the centerof the leak area. If the exact location of the gas main is not known,the sampling boom might pass over the outer perimeter of the area wheregas it venting to the atmosphere. In this situation, not only is theconcentration of the gas in the sample apt to be low, but the period oftime that the sampling funnel 116 would be over a venting area is alsoreduced. Under these circumstances, it would be possible to miss a largeleak if the sampling system was not eflicient. These points illustratethe necessity of an eflicient sampling method and apparatus as isdisclosed in the present invention. The funnel 16 in the primarysampling system increases the scope or sampling area of the unit, Whilethe secondary sampling system carries the gas sample to a point near theanalyzer 14 with minimum dilution and in the shortest possible time.

It will be seen that the gas analyzer produces an indication of methanegas on the chart paper 184, and such indication can be quickly locatedrelative to the land marks 185 because of the fifty foot markings 193made on the chart paper 184.

The actual speed of the vehicle in feet per minute, and total footagecovered are simultaneously recorded with the gas detections and a scaleis established on the chart paper 184 which compensates for anyvariation in the speed of travel. Experience has shown that the mobilegas detecting unit of the present invention is an accurate and efiicientdetector, of pre-selected gases. It will be seen that the nozzle 134 forthe secondary sampling system is disposed in the throat of the funnel 16at a higher level than the lower intake end of the funnel 16. The pointof intake or the primary sampling system thus is located at a pointspaced below the point of intake of the secondary sampling system. Forexample, as shown in FIG. 14, in one embodiment the height of theconnector pipe 221 was 2 /2", the height of the throat portion 220 was 4/8", and the height of the intake portion 219 was 2%". The nozzle 134extended down into the throat 220 for a distance of 2" and the lower endof the nozzle was thus about 4 /2" above the intake point or lower endof the funnel 16.

While it will be apparent that the preferred embodiments of theinvention herein disclosed are well calculated to fulfill the objectsabove stated, it will be appreciated that the invention is susceptibleto modification, variation and change without departing from the properscope or fair meaning of the subjoined claims.

What we claim is:

1. A mobile gas leakage detecting apparatus for detecting and chartingthe location of leaks of a preselected gas through the surface of theground comprising: a vehicle adapted to move over the ground along apredetermined survey route; a gas sample pick-up apparatus operativelymounted on said vehicle; a suction means for drawing gas samples throughsaid gas pick-up apparatus; gas concentration analyzer means mounted insaid vehicle for measuring the concentration of said preselected gas inthe gas samples drawn by said suction means; recording means including achart and a first and second stylus; said recording means beingresponsive to said gas concentration analyzing means for recording theconcentrations of said preselected gas on said chart by means of firststylus; means for moving said recorder chart at a constant speedindependent of the speed of said vehicle; fifth wheel means mounted onsaid vehicle to be rotated at a speed proportional to the speed of saidvehicle; a worm gear coupled'to said fifth wheel means to be driventhereby; means coupled between said worm gear and said fifth wheel meansto cause one complete revolution of said worm gear for each one foot oftravel of the vehicle; a source of electrical power connected to saidsecond stylus; a pinion gear meshed with said worm gear; switch meansfor connecting the second stylus to said electrical power source foractuating said stylus to produce indicator marks; and a switch operatingmember on said pinion gear for momentarily closing said switch means,whereby when said worm gear makes a predetermined number of revolutions,the pinion gear make one complete revolution and said switch operatingmember will momentarily close said switch means and actuate said secondstylus to produce a distance indicator mark on said chart, whereby acontinuous strip chart is produced which shows detected gas leaks inreference to the distance traveled by the vehicle.

2. A mobile gas leakage detecting apparatus as defined in claim 1,wherein said means coupled between said fifth wheel means and said wormgear comprises a gear reduction means.

References Cited UNITED STATES PATENTS 778,451 12/1904 Hartley et al.34633 1,444,886 2/ 1923 Rounds. 2,290,618 7/1942 Bosomworth 731462,834,113 5/1958 En Dean et a1. 34633 2,879,663 3/1959 Thomas 73263,107,517 10/1963 Loyd et a1. 73-23 RICHARD C. QUEISSER, PrimaryExaminer.

1. A MOBILE GAS LEAKAGE DETECTING APPARATUS FOR DETECTING AND CHARTINGTHE LOCATION OF LEAKS OF A PRESELECTED GAS THROUGH THE SURFACE OF THEGROUND COMPRISING: A VEHICLE ADAPTED TO MOVE OVER THE GROUND ALONG APREDETERMINED SURVEY ROUTE; A GAS SAMPLE PICK-UP APPARATUS OPERATIVELYMOUNTED ON SAID VEHICLE; A SUCTION MEANS FOR DRAWING GAS SAMPLES THROUGHSAID GAS PICK-UP APPARATUS; GAS CONCENTRATION ANALYZER MEANS MOUNTED INSAID VEHICLE FOR MEASURING THE CONCENTRATION OF SAID PRESELECTED GAS INTHE GAS SAMPLES DRAWN BY SAID SUCTION MEANS; RECORDING MEANS INCLUDING ACHART AND A FIRST AND SECOND STYLUS; SAID RECORDING MEANS BEINGRESPONSIVE TO SAID GAS CONCENTRATION ANALYZING MEANS FOR RECORDING THECONCENTRATIONS OF SAID PRESELECTED GAS ON SAID CHART BY MEANS OF FIRSTSTYLUS; MEANS FOR MOVING SAID RECORDER CHART AT A CONSTANT SPEEDINDEPENDENT OF THE SPEED OF SAID VEHICLE; FIFTH WHEEL MEANS MOUNTED ONSAID VEHICLE TO BE ROTATED AT A SPEED PROPORTIONAL TO THE SPEED OF SAIDVEHICLE; A WORM GEAR COUPLED TO SAID FIFTH WHEEL MEANS TO BE DRIVEN